How Do Substances Work in the Brain to Produce Pleasure?

Nearly all substances directly or indirectly target the brain’s reward system by flooding the circuit with dopamine. Dopamine is a neurotransmitter present in regions of the brain that regulate movement, emotion, cognition, motivation, and reinforcement of rewarding behaviors. When activated at normal levels, this system rewards our natural behaviors. Overstimulating the system with substance, however, produces effects which strongly reinforce the behavior of substance use, teaching the person to repeat it.